Long-term deformations and cracking risk of concrete with high content of mineral additions

Abstract

This paper presents results from a study on long-term deformations of concrete with a high content of mineral additions, such as blast-furnace slag and fly ash. Autogenous and drying shrinkage were monitored. The kinetics and magnitude of these deformations are modified by the type and content of mineral additions. This behaviour is mainly due to the slow advancement of their hydration reaction and to the evolution of their microstructure during the first days. Mechanical properties were also affected by mineral additions. All these modifications led to an increase in cracking susceptibility of concrete mixtures with blast-furnace slag. But their optimisation in terms of mechanical performance allowed reducing their cracking risk. An analytical model (Eurocode 2) was also applied for comparison. The prediction of the total shrinkage of the studied concrete mixtures was found to be satisfactory, but the autogenous shrinkage of concrete mixtures with mineral additions was significantly underestimated.